If bid price is 100$ and Ask price is 101$, and the trade happens at 101 $, can I conclude that the buying pressure is more than the selling?
If the trade happens on above average volume, (e.g more than 5 times the average volume of a transaction), is it safe to say that the next trade will take place at a higher price, since the immediate trend is bullish?
I understand of course that if bid and ask spread is too low, then this conclusion is not valid.
No, you can't conclude anything about buying vs. selling pressure from a single trade. However, buy and sell pressures are straightforward to compute on your own by monitoring the exchange's order publications. Excepting for hidden orders, you can always know the prices and total quantities of resting buy and sell orders on the exchange. (Of course, your information will almost certainly be at least several seconds out-of-date relative to that of the major market players, whose machines are located right next to the exchanges.)
There is probably some (very) slight correlation between the existence of a large trade in one direction and the sign of the price change for some future trades. However, you almost certainly won't be able to take advantage of this information (if there even is any advantage to be taken) because faster market participants will have already reacted (some wisely, some unwisely) by the time you find out about the trade in question.
One moral is that profiting off of ephemeral bits of information in the market is essentially impossible for small traders. But the larger moral is to question why you want to do so. The amount of money one can make by timing the market on a millisecond-by-millisecond basis is so small that it only pays to do so if you have vast sums of money to invest.
Yes, at that precise moment, the trend is bullish, but considering the random walk theory, the next price is just as random as before.
There are many days where the entire volume is at a higher or lower price, and at the end of the day, course is reversed on low volume. This can be seen when an attempted market manipulator gives up or runs out of capital, stops trading, and the market immediately starts to revert to the mean on lesser volume.
